Glow discharge display device with intersecting electrode systems sealed between opposing plates

ABSTRACT

A glow discharge display panel comprising a pair of parallel plates between and parallel to which extend first and second sets of elongate conductors with conductors of the first set crossing those of the second set forming a cross-bar addressing system for the array of gas discharge paths defined by the effective crosspoints of the conductors of the first set with those of the second. These discharge paths are physically isolated from each other by an interlocking system of ridges (which may be replaced by rods) and posts provided on the facing surface of the plates. The posts extend between the conductors of the first set towards the second plate so that each part of each conductor of the second set which links a pair of adjacent cross-points is situated between the end of a post and the second plate. The ridges or rods extend between the posts of the ends of which face each conductor of the second set and the posts the ends of which face the or each adjacent conductor of the second set. The posts and ridges or rods are preferably opaque.

United States Patent 11 1 Weston 14 1 Aug. 19, 1975 [75] Inventor: George Frederick Weston, Salfords,

near Redhill, England [73] Assignee: U.S. Philips Corporation, New

York, N.Y,

[22] Filed: Nov. 1, I973 21 Appl. N0; 4|],760

(30] Foreign Application Priority Data Nov. 20, 1972 United Kingdom 53508/72 [52l US. Cl. 3l3/l88; 3l3/l90; 3l3/220; 3l5/l69 TV [5|] Int. Cl. H0lj 17/00 [58] Field of Search 3l3/l88, I90, 210, 220; 3l5/I69 TV [56] References Cited UNITED STATES PATENTS 3,700,946 Ill/I972 Cums 3l3/l83 3,803,439 4/l974 Sasaki et a] 3l3/l88 Primary Ii.\'un1inerEli Lieberman Attorney, Agenl, or Firm-Frank R. Trifari; Carl P. Steinhauser [57] ABSTRACT A glow discharge display panel comprising a pair of parallel plates between and parallel to which extend first and second sets of elongate conductors with conductors of the first set crossing those of the second set forming a cr0ss-bar addressing system for the array of gas discharge paths defined by the effective cross-points of the conductors of the first set with those of the second. These discharge paths are physically isolated from each other by an interlocking system of ridges (which may be replaced by rods) and posts provided on the facing surface of the plates. The posts extend between the conductors of the first set towards the second plate so that each part of each conductor of the second set which links a pair of adjacent cross-points is situated between the end of a post and the second plate. The ridges or rods extend between the posts of the ends of which face each conductor of the second set and the posts the ends of which face the or each adjacent conductor of the second set. The posts and ridges or rods are preferably opaque.

10 Claims, 6 Drawing Figures GLOW DISCHARGE DISPLAY DEVICE WITH INTERSECTING ELECTRODE SYSTEMS SEALED BETWEEN OPPOSING PLATES This invention relates to a glow-discharge display device comprising first and second substantially parallel electrically insulating plates facing one another with a discharge gas atmosphere between them, a first and second sets of elongate electrical conductors extending between and substantially parallel to the plates with the conductors of the first set spaced from and crossing those of the second set to form a cross-bar addressing system for the resulting array of electric discharge paths through said atmosphere defined by the effective cross-points of the conductors of the first set with those of the second.

It is desirable with such devices that some form of optical and electrical isolation be provided between adjacent discharge paths. To this end a construction is known in which a third plate is sandwiched between the other two, this third plate being provided with perforations aligned with the cross-points so that the discharge paths extend through them. Such a construction can give rise to problems of accurate alignment of the perforations with the cross-points. In an alternative form of construction the conductors of one set have a plate of insulating material moulded around them, a cavity being moulded in one major face of the plate at the location of each cross-point, these cavities extending into the plate so that the corresponding conductor is exposed at the base thereof. Electrodes electrically connected to the conductors of the other set face the open ends of the cavity and the luminous part of the discharge can, in operation, be substantially confined to the corresponding cavity. Problems can however, also arise with this form of construction especially when moulding the plate with its cavities around the corresponding set of conductors. This is particularly so when the plate is large and has to be provided with a large number of cavities.

It is an object of the invention to provide an alternative construction of glow-discharge display device which still allows substantial isolation between the discharge paths to be obtained.

The invention provides a glow-discharge display device comprising first and second substantially parallel electrically insulating plates facing one another with a discharge gas atmosphere between them, first and second sets of elongate electrical conductors extending between and substantially parallel to the plates with the conductors of the first set spaced from and crossing those of the second set to form a cross-bar addressing system for the resulting array of electric discharge paths through said atmosphere defined by the effective cross-points of the conductors of the first set with those of the second. that surface of the first plate which faces the second plate having an array of electrically insulating posts thereon which extend between the conductors of the first set towards the second plate, the conductors of the second set running between the ends of said posts and the second plate so that each part of each conductor of the second set which links a pair of adjacent said cross-points is situated between the end of an individual post and the second plate, and electrically insulating material extending in the length direction of the conductors of the second set between these posts the ends of which face each conductor of the second set and those posts the ends of which face the or each adjacent conductor of the second set.

The posts may be islands left by providing first and second sets of parallel grooves at an angle to one another in the surface of the first plate which faces the second plate. Similarly the electrically insulating material extending in the length direction of the conductors of the second set of conductors may be in the form of ridges formed by providing parallel grooves in the surface of the second plate which faces the first plate. The grooves may be provided by means of a numerically controlled machine tool.

As an alternative the posts and/or ridges may be built up by silk screen printing using suitably electrically insulating inks which are later fired in the manner of the technology employed for thick film circuits, the required height of the posts and/or ridges being obtained by the application of several printed layers one on the other.

In order to provide some degree of optical isolation between adjacent discharge paths preferably the posts, the first plate, and the insulating material extending in the length direction of the conductors of the second set of conductors are opaque and the second plate is transparent. If said insulating material is opaque and the second plate is transparent then said material is preferably formed by rods laid between the corresponding posts, rather than by providing parallel grooves in the relevant surface of the second plate, because the latter method would necessitate using a laminated (part opaque, part transparent) starting plate unless the silk screen printing method is employed.

Embodiments of the invention will now be described by way of example, with reference to the accompanying diagrammatic drawings, in which:

FIG. I is a perspective view of a first plate and a first set of conductors;

FIG. 2 is a perspective view of a second plate and a second set of conductors;

FIGS. 3 and 4 are cross-sections of part of a glowdischarge display device including the plates and conductors of FIGS. 1 and 2', and

FIGS. 5 and 6 are cross-sections of part of an alternative glow-discharge display device.

In FIG. I an opaque electrically insulating glass plate 1 has a square array of posts 2 on its upper surface. The posts have been produced by machining two orthogonal sets of parallel grooves 4 and 5 in this upper surface. A parallel electrically conductive cathode strip 3 is provided in each groove 4 of one set.

FIG. 2 shows a second electrically insulating glass plate 6 which is transparent and has parallel ridges 7 formed on its upper surface by providing a set of parallel grooves 8 in this surface. The grooves 8 correspond with the posts 2 of FIG. 1 so the ridges 7 can fit snugly into the grooves 5. An anode wire 9 is provided in each groove 8. The ridges 7 are opaque, the starting material for the plate 6 and ridges 7 having been a part opaque, part transparent laminated plate, the grooves 8 being in the opaque lamination and having a depth equal to the thickness thereof.

In FIGS. 3 and 4 the assembly including the plate 6 of FIG. 2 has been inverted and the ridges 7 have been slotted into the grooves S of the assembly of FIG. 1 to form an electric glow discharge display device. FIG. 3 is a crosssection taken along IIIIII in FIGS. I and 3 and FIG. 4 is a cross-section taken along IVlV in FIGS. 1 and 2.

It will be seen that the interlocking of the posts 2 and ridges 7 has produced an array of cavities (FIG. 3) each bounded by a pair of posts 2 and a pair of ridges 7 and each coinciding with the cross-point of a strip 3 and a wire 9. It will also be seen from HO. 3 that the cathode strips 3 are clamped between the tops of the ridges 7 and the plate 1. Similarly it will be seen from FIG. 4 that the anode wires 9 are clamped between the tops of the posts 2 and the plate 6, those parts of the wires 9 which are so clamped lying between adjacent discharge cavities 10. A ridge 7 runs between those posts 2 the ends of which face each wire 9 and those posts 2 the ends of which face the or each adjacent wire 9.

The two plates are sealed all round by means of glaze 11 and the spaces between them filled with a suitable electric glow-discharge gas atmosphere, for example a Penning gas atmosphere or pure neon at a pressure of several hundred Torr, together with a little mercury vapour.

In order to avoid differential expansion effects the various components of the device preferably all have approximately the same coefficient of thermal expansion. To this end the components 1, 2 and 7 may be made of glass, for example, a glass available under the Registered Trade Mark FUSITE K, the plate 6 may be made of glass, for example, a glass available under the type number 7059 CORNING," and the strips 3 and wires 9 may be made of an iron-nickel-cobalt alloy, for example an alloy available under the Registered Trade Mark KOVAR."

The spacing between the strips 3 and wires 9 may be 0.6 mm at their cross-points and the section of each cavity 10 taken perpendicular to the discharge path through it may be a square of 0.8 mm wide. The posts 2 may also be square.

In operation any discharge cavity 10 may be addressed by applying an operating potential of i.e. +250 volts to the corresponding anode wire 9 relative to the corresponding cathode strip 3, to produce a luminous discharge therein, sequential energization of selected cavities building up a required display. it will be evident that a practical device will normally have more than the twenty discharge cavities of the device illustrated.

FIGS. 5 and 6 are cross-sections, similar to those of FIGS. 3 and 4 respectively, of an alternative construction to that shown in H68. 1 to 4 in which the ridges 7 have been replaced by opaque electrically insulating glass rods 12 laid between the posts 2. Otherwise the construction is similar to that shown in FIGS. 1 to 4. The rods 12 may for example, be of rectangular or circular cross-section and preferably fit snugly into the corresponding groove 5 (FIG. 1) and contact the (now substantially flat) plate 6.

What is claimed is:

l. A glow discharge display device comprising first and second substantially parallel electrically insulating plates facing one another with a discharge gas atmosphere bctween them, first and second sets of elongate electrical conductors extending between and substantially parallel to the plates with the conductors of the first set spaced from and crossing those of the second set to form a cross'bar addressing system for the resulting array of electric discharge paths through said atmosphere defined by the effective cross-points of the conductors of the first set with those of the second, the surface of the first plate which faces the second plate comprising an array of electrically insulating posts thereon which extend between the conductors of the first set towards the second plate, the conductors of the second set running between the end of said posts and the second plate so that each part of each conductor of the second set which links a pair of adjacent said crosspoints is situated between the end of an individual post and the second plate, and members on said second plate of electrically insulating material extending in the length direction of the conductors of the second set to fill the space formed by the array of insulating posts in the direction perpendicular to the first set of conductors.

2. A device as claimed in claim I, wherein the material of the first plate and the posts is substantially opaque and the material of the second plate is substantially transparent.

3. A device as claimed in claim I wherein said members of electrically insulating material extend between each conductor of the second set and each adjacent conductor of the second set.

4. A device as claimed in claim 3, wherein said members of electrically insulating material are in the form of ridges on that surface of the second plate which faces the first plate.

5. A device as claimed in claim 4, wherein said ridges are formed by parallel grooves provided in the surface of the second plate which faces the first plate.

6. A device as claimed in claim 4 wherein said ridges are substantially opaque.

7. A device as claimed in claim I, wherein said members of electrically insulating material are in the form of substantially opaque rods laid between the corresponding posts.

8. A device as claimed in claim 1, wherein the conductors of the first set are clamped between the first plate and the members of electrically insulating material.

9. A device as claimed in claim 1 wherein the conductors of the second set are clamped between the second plate and the ends of the posts.

10. A device as claimed in claim 1 wherein the posts are formed by islands between first and second sets of parallel grooves provided at an angle to one another in the surface of the first plate which faces the second plate.

t m w i n 

1. A glow discharge display device comprising first and second substantially parallel electrically insulating plates facing one another with a discharge gas atmosphere between them, first and second sets of elongate electrical conductors extending between and substantially parallel to the plates with the conductors of the first set spaced from and crossing those of the second set to form a cross-bar addressing system for the resulting array of electric discharge paths through said atmosphere defined by the effective cross-points of the conductors of the first set with those of the second, the surface of the first plate which faces the second plate comprising an array of electrically insulating posts thereon wHich extend between the conductors of the first set towards the second plate, the conductors of the second set running between the end of said posts and the second plate so that each part of each conductor of the second set which links a pair of adjacent said cross-points is situated between the end of an individual post and the second plate, and members on said second plate of electrically insulating material extending in the length direction of the conductors of the second set to fill the space formed by the array of insulating posts in the direction perpendicular to the first set of conductors.
 2. A device as claimed in claim 1, wherein the material of the first plate and the posts is substantially opaque and the material of the second plate is substantially transparent.
 3. A device as claimed in claim 1 wherein said members of electrically insulating material extend between each conductor of the second set and each adjacent conductor of the second set.
 4. A device as claimed in claim 3, wherein said members of electrically insulating material are in the form of ridges on that surface of the second plate which faces the first plate.
 5. A device as claimed in claim 4, wherein said ridges are formed by parallel grooves provided in the surface of the second plate which faces the first plate.
 6. A device as claimed in claim 4 wherein said ridges are substantially opaque.
 7. A device as claimed in claim 1, wherein said members of electrically insulating material are in the form of substantially opaque rods laid between the corresponding posts.
 8. A device as claimed in claim 1, wherein the conductors of the first set are clamped between the first plate and the members of electrically insulating material.
 9. A device as claimed in claim 1 wherein the conductors of the second set are clamped between the second plate and the ends of the posts.
 10. A device as claimed in claim 1 wherein the posts are formed by islands between first and second sets of parallel grooves provided at an angle to one another in the surface of the first plate which faces the second plate. 